If you have any copies of AS&T lying around the authorised skywatcher dealers usually have there names listed in ads for Skywatcher equipment. There are others apart from the two you have listed - NVT which run
www.telescopeshop.com.au, Sirius Optics, Star Optics, myastroshop.com.au plus others. As far as i am aware Andrews are the only store that are not authorised and are selling the products and have also heard Tasco are not happy about it and are looking at ways to stop them. Most retailers will match Andrews prices however, so i see it as maybe a good thing for competition and the consumer as i'm led to believe Tasco and most authorised importers of astro gear put a large markup of products Andrews don't have. So if you want to take a chance with no warranty i've read lots of people here who are very happy with Andrews then give them a try. Personally i wouldn't have a problem buying most stuff from them. Eyepieces, OTA's etc should be uniformally ok. My problem would come when purchasing motorised mounts or the like that have a higher chance of failure.
Others here will know far more about this than me so see what others say and feel free to correct me if what i've said isn't exactly correct.